[The action of the polypeptide placental hormones HCG and HCS on the blastic changes of lymphocytes in mixed cultures].

The present work studies the effect of the placental hormones HCG and HCS on cellular immunity in vitro. These two hormones used in identical or greater concentrations than found in circulating blood inhibit lymphoblastic changes in mixed cultures of lymphocytes. It is possible that HCG and HCS have the same inhibiting effect in vivo on immunity by cellular mediation in the pregnant woman. This inhibition could be of the greatest importance at the surface of the trophoblast where their concentration is probably raised, and where contact between fetal antigens and maternal blood also takes place.